Process for producing a chip

ABSTRACT

A process for producing a chip, comprising the steps of: 
     setting an object to be diced on a pressure sensitive adhesive sheet for producing chip comprising at least one layer of shrinkable film, an expansible film and a pressure sensitive adhesive layer for setting the object; 
     fixing edges of the pressure sensitive adhesive sheet for producing chip; 
     dicing the object into chips, and 
     shrinking the shrinkable film to thereby expand chip spacings. In the process for producing small chips such as semiconductor chips, chip spacings can be expanded without the need to conduct the conventional expansion step.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of patent application Ser. No.09/019,608 filed Feb. 6, 1998, now U.S. Pat. No. 6,312.800, issued Nov.6, 2001, which claimed priority under 35 U.S.C. §119 of JapaneseApplication No. 9-026571 filed Feb. 10, 1997.

FIELD OF THE INVENTION

The present invention relates to a process for producing a chip and apressure sensitive adhesive sheet for producing chip. More particularly,the present invention is concerned with a process for producing smallchips such as semiconductor chips in which chip spacings can be expandedwithout the need to conduct the conventional expansion step and apressure sensitive adhesive sheet for producing chip suitably employedin this process.

BACKGROUND OF THE INVENTION

A semiconductor wafer of, for example, silicon or gallium arsenide isproduced in a large diameter, cut and separated (diced) into elementalchips and subjected to the subsequent mounting step. In this process,the semiconductor wafer undergoes dicing, expansion and picking-up stepsin the state of being attached to a pressure sensitive adhesive sheetand is transferred to the subsequent mounting step.

In the expansion step, the pressure sensitive adhesive sheet is extendedso that chip spacings are expanded. The objective of the expansion stepin which chip spacings are expanded is to facilitate chip recognition inthe die bonding and to prevent device breakage attributed to abuttal ofneighboring chips in the pickup step.

Currently, the expansion step is carried out by extending the pressuresensitive adhesive sheet with the use of an expanding apparatus.

In most expanding apparatuses, the degree of extension and the torqueduring the extension are fixed to thereby render difficult adjustingdependent upon the type of pressure sensitive adhesive sheet and thesize of device.

Accordingly, it has occurred that, when the pressure sensitive adhesivesheet is soft, the extending stress is not conveyed to the objectsetting portion to thereby disenable attaining satisfactory chipspacings and that, on the other hand when the pressure sensitiveadhesive sheet is hard, the torque of the apparatus is unsatisfactory orthe pressure sensitive adhesive sheet is torn.

Further, when the die bonding is completed, the pressure sensitiveadhesive sheet is housed, in the state of being set on a ring frame,into a ring frame cassette. In the conventional process, the pressuresensitive adhesive sheet having been deformed by the expansion must haveits shape restored to the original by the use of hot air. When therestoration of the shape is unsatisfactory, the pressure sensitiveadhesive side of the pressure sensitive adhesive sheet occasionallyadheres to the ring frame cassette to thereby disenable housing thereof.Thus, an automization has been difficult.

The present invention has been made with a view toward resolving theabove problem of the prior art. An object of the present invention is toprovide a process for producing a chip in which chip spacings can beexpanded according to mechanism which is radically different from theconventional expansion method, and another object of the presentinvention is to provide a pressure sensitive adhesive sheet forproducing chip suitably employed in the above process.

SUMMARY OF THE INVENTION

The process for producing a chip according to the present inventioncomprises the steps of:

setting an object to be diced on a pressure sensitive adhesive sheet forproducing chip comprising at least one layer of shrinkable film, anexpansible film and a pressure sensitive adhesive layer for setting theobject;

fixing edges of the pressure sensitive adhesive sheet for producingchip;

dicing the object into chips, and

shrinking the shrinkable film to thereby expand chip spacings.

The pressure sensitive adhesive sheet for producing chip of the presentinvention is suitably used in the above process and comprises a zone forsetting an object to be diced including an expansible film and apressure sensitive adhesive layer for setting the object and a shrinkagezone including at least one layer of shrinkable film, wherein theshrinkage zone is arranged at least outside the zone for setting theobject.

Preferred pressure sensitive adhesive sheet for producing chip is, forexample, one wherein the pressure sensitive adhesive layer for settingthe object, the shrinkable film and the expansible film are laminated inthis order as shown in FIG. 1 or one wherein the pressure sensitiveadhesive layer for setting the object, the expansible film and theshrinkable film are laminated in this order as shown in FIG. 2.

In the present invention, it is preferred that the expansible film havean elastic modulus of less than 1×10⁹ N/m² and that the pressuresensitive adhesive layer for setting the object be composed of aradiation curable pressure sensitive adhesive.

Further, it is preferred that the shrinkable film and the expansiblefilm are laminated via an adhesive layer having an elastic modulus of atleast 1.0×10⁵ N/m².

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1 to 7 show variety of pressure sensitive adhesive sheet forproducing chip for use in the present invention; and.

FIGS. 8 and 9 show process for producing a chip according to the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The process for producing a chip and the pressure sensitive adhesivesheet for producing chip according to the present invention will bedescribed in detail below.

In the process for producing a chip according to the present invention,use is made of a pressure sensitive adhesive sheet for producing chipcomprising at least one layer of shrinkable film, an expansible film anda pressure sensitive adhesive layer for setting the object. Although theshrinkable film is not particularly limited, a thermally shrinkable filmis preferentially employed.

The shrinkage ratio of the shrinkable film employed in the presentinvention preferably ranges from 10 to 90% and, still preferably, from20 to 80%. The shrinkage ratio is calculated from the size prior toshrinkage and the size after shrinkage by the following formula:${{Shrinkage}\quad {ratio}\quad (\%)} = {\frac{\left\lbrack {\left( {{size}\quad {prior}\quad {to}\quad {shrinkage}} \right) - \left( {{size}\quad {after}\quad {shrinkage}} \right)} \right\rbrack}{\left( {{size}\quad {prior}\quad {to}\quad {shrinkage}} \right)} \times 100.}$

In the use of the thermally shrinkable film, the above shrinkage ratiois calculated from the sizes of the film prior to and after heating at120° C.

Various shrinkable films of the above type are known, and any thereofcan be used in the present invention as long as the object does notsuffer from adverse effects such as ion contamination therefrom.Examples of suitable shrinkable films include uniaxially and biaxiallyoriented films such as those of polyethylene terephthalate,polyethylene, polystyrene, polypropylene, polyamide, polyurethane,polyvinylidene chloride and polyvinyl chloride. These shrinkable filmscan be used in combination.

The thickness of the above shrinkable film generally ranges from 5 to300 μm, preferably, from 10 to 200 μm.

In particular, thermally shrinkable polyethylene, polypropylene andpolyethylene terephthalate films are preferably used as the shrinkablefilm.

The substrate of the pressure sensitive adhesive sheet for producingchip for use in the process of the present invention is a combination ofthe above shrinkable film and an expansible film.

Although the expansible film is not particularly limited, it ispreferred that the expansible film have high water and heat resistancesand be composed of a synthetic resin.

Examples of suitable expansible films include films of low densitypolyethylene (LDPE), linear low density polyethylene (LLDPE),ethylene/propylene copolymer, polypropylene, polybutene, polybutadiene,polymethylpentene, ethylene/vinyl acetate copolymer,ethylene/(meth)acrylic acid copolymer, ethylene/methyl (meth)acrylatecopolymer, ethylene/ethyl (meth)acrylate copolymer, polyvinyl chloride,vinyl chloride/vinyl acetate copolymer, ethylene/vinyl chloride/vinylacetate copolymer, polyurethanes, polyamides and ionomers. Theseexpansible films can be used in combination. Moreover, use can be madeof a film of a polymer of a compound having a carboxyl group as apolymer structure unit and a laminate of this film and a generallyemployed polymer film.

The thickness of the above expansible film generally ranges from 5 to500 μm, preferably, from 10 to 300 μm.

It is generally preferred that the elastic modulus at 23° C. of theexpansible film for use in the present invention be less than 1×10⁹N/m², especially, in the range of 1×10⁷ to 1×10⁹ N/m².

The side brought into contact with another layer of the shrinkable filmor expansible film may be provided with corona treatment or may have aprimer or other layer attached thereto for improving the adherence.

In the present invention, the pressure sensitive adhesive layer forsetting the object may be irradiated with ultraviolet rays prior to orafter shrinking the films, as described later. When the irradiation iseffected, the films constituting the substrate must be transparent.

The pressure sensitive adhesive layer for setting the object of thepressure sensitive adhesive sheet for producing chip can be producedfrom various conventional pressure sensitive adhesives. These pressuresensitive adhesives are not particularly limited and some examplesthereof include pressure sensitive adhesives based on a rubber, anacrylic, a silicone and a polyvinyl ether. Also, use can be made ofpressure sensitive adhesives which are curable by radiation and pressuresensitive adhesives which foam when heated. Further, use can be made ofadhesives usable in both dicing and die bonding.

Although depending on the properties of the materials thereof, thethickness of the pressure sensitive adhesive layer for setting theobject generally ranges from about 3 to 100 μm, preferably, from about10 to 50 μm.

As mentioned above, various pressure sensitive adhesives are usedwithout any particular limitation. For example, those described inJapanese Patent Publication Nos. 1(1989)-56112 and 7(1995)-15087 andJapanese Patent Laid-Open Publication No. 7(1995)-135189 can preferablybe used as the pressure sensitive adhesives curable by radiation(curable by light, ultraviolet rays or electron beams), which, however,do not limit the radiation curable pressure sensitive adhesives for usein the present invention. Nevertheless, the use of pressure sensitiveadhesives curable by ultraviolet rays is especially preferred in thepresent invention.

In the present invention, the shrinkable film and the expansible filmare bonded together in various configurations as described below. Thepressure sensitive adhesive layer for setting the object can be used inthe film bonding, as shown in FIGS. 3 to 5. Also, other adhesive layerscan be applied as shown in FIGS. 1, 2, 6 and 7. This adhesive is notparticularly limited and generally used adhesives may be employed.Examples of suitable adhesives include adhesives such as those based onan acrylic, a rubber and a silicone; thermoplastic or thermosettingadhesives such as those based on a polyester, a polyamide, an ethylenecopolymer, an epoxy and a urethane; and adhesive curable by ultravioletrays on electron beams such as those based on an acrylic and a urethane.Especially, it is preferred to employ the adhesive having an elasticmodulus of at least 1.0×10⁵ N/m², preferably at least 1.0×10⁷ N/m². Theuse of such adhesive enables the uniform shrinkage of shrinkable film toprevent the exposure of the adhesive, thereby smoothly picking up thechips. The film bonding can be effected without the use of an adhesive,for example, by laminating the shrinkable film to the expansible filmaccording to, for example, the heat seal technique.

When the shrinkable film is arranged at a position where the ring frameis fixed as shown in FIGS. 3 and 5, a pressure sensitive adhesive layerfor immobilizing the ring frame can be disposed on the shrinkable film.The pressure sensitive adhesive layer for immobilizing the ring framecan be composed of the same various conventional pressure sensitiveadhesives as in the pressure sensitive adhesive layer for setting theobject.

The pressure sensitive adhesive sheet for producing chip is used in thestate of having an object to be diced set on the pressure sensitiveadhesive layer for setting the object at the zone for setting the objectand in the state of having its edges fixed by means of, for example, aring frame. The set object is diced into chips, and the shrinkable filmis shrunk. Then, an extending stress is generated by the shrinkable filmarranged outside the zone for setting the object (shrinkage zone) tothereby expand chip spacings. In this process of the present invention,it is preferred that the shrinkable film of the pressure sensitiveadhesive sheet for producing chip be arranged at least outside the zonefor setting the object.

Preferred structures of the pressure sensitive adhesive sheets 10 forproducing chip for use in the present invention together with thepositional relationships of the ring frame 5 and the object 6 are asshown in FIGS. 1 to 7. Actual Examples and preferred forms of thepressure sensitive adhesive layers 1 for setting the object, shrinkablefilms 2, adhesive layers 3 and expansible films 4 are as describedabove. The adhesive layer 3 is not always essential as mentioned above.

In the pressure sensitive adhesive sheet 10 for producing chip of FIG.1, the shrinkable film 2 is laminated through the adhesive layer 3 to anentire surface of the expansible film 4, and the pressure sensitiveadhesive layer 1 for setting the object 6 is disposed on the oppositeentire surface of the shrinkable film 2. Edges of the pressure sensitiveadhesive sheet 10 for producing chip are fixed by means of the ringframe 5 on the pressure sensitive adhesive layer 1 for setting theobject 6 at its periphery. The object 6 is set on the pressure sensitiveadhesive layer 1 for setting the object 6 inside its periphery.

In the pressure sensitive adhesive sheet 10 for producing chip of FIG.2, the expansible film 4 is laminated through the adhesive layer 3 to anentire surface of the shrinkable film 2, and the pressure sensitiveadhesive layer 1 for setting the object 6 is disposed on the oppositeentire surface of the expansible film 4. Edges of the pressure sensitiveadhesive sheet 10 for producing chip are fixed by means of the ringframe 5 on the pressure sensitive adhesive layer 1 for setting theobject 6 at its periphery. The object 6 is set on the pressure sensitiveadhesive layer 1 for setting the object 6 inside its periphery.

In the pressure sensitive adhesive sheet 10 for producing chip of FIG.3, the pressure sensitive adhesive layer 1 for setting the object 6 isdisposed on the expansible film 4, and the shrinkable film 2 islaminated to a peripheral part of the pressure sensitive adhesive layer1 for setting the object 6. The pressure sensitive adhesive sheet 10 forproducing chip on its shrinkable film 2 is fixed by means of the ringframe 5, and the object 6 is set on the pressure sensitive adhesivelayer 1 for setting the object 6. In this structure, it is preferredthat the pressure sensitive adhesive layer 9 for immobilizing the ringframe be applied onto the shrinkable film 2.

In the pressure sensitive adhesive sheet 10 for producing chip of FIG.4, the pressure sensitive adhesive layer 1 for setting the object 6 isdisposed on the expansible film 4, and the shrinkable film 2 islaminated onto the pressure sensitive adhesive layer 1 for setting theobject 6 outside the zone for setting the object 6 but inside the partwhere the pressure sensitive adhesive sheet 10 for producing chip isfixed. Edges of the pressure sensitive adhesive sheet 10 for producingchip are fixed by means of the ring frame 5 on the pressure sensitiveadhesive layer 1 for setting the object 6 at its periphery. The object 6is set on the pressure sensitive adhesive layer 1 for setting the object6 inside its periphery.

In the pressure sensitive adhesive sheet 10 for producing chip of FIG.5, the pressure sensitive adhesive layer 1 for setting the object 6 isdisposed on the expansible film 4, and the shrinkable film 2 islaminated with its outer periphery protruding onto the pressuresensitive adhesive layer 1 for setting the object 6 at its periphery.The pressure sensitive adhesive sheet 10 for producing chip is fixed bymeans of the ring frame 5 on the protruding outer periphery of theshrinkable film 2, and the object 6 is set on the pressure sensitiveadhesive layer 1 for setting the object 6. In this structure, it ispreferred that the pressure sensitive adhesive layer 9 for immobilizingthe ring frame be applied onto the shrinkable film 2.

In the pressure sensitive adhesive sheet 10 for producing chip of FIG.6, the shrinkable film 2 is laminated through the adhesive layer 3 ontothe periphery of the lower side of the expansible film 4, and thepressure sensitive adhesive layer 1 for setting the object 6 is disposedon the upper side of the expansible film 4. Edges of the pressuresensitive adhesive sheet 10 for producing chip are fixed by means of thering frame 5 on the pressure sensitive adhesive layer 1 for setting theobject 6 at its periphery. The object 6 is set on the pressure sensitiveadhesive layer 1 for setting the object 6 inside its periphery.

In the pressure sensitive adhesive sheet 10 for producing chip of FIG.7, the shrinkable film 2 is laminated through the adhesive layer 3 ontopart of the lower side of the expansible film 4, which part locatesoutside the zone for setting the object and inside the zone where thepressure sensitive adhesive sheet 10 for producing chip is fixed. Thepressure sensitive adhesive layer 1 for setting the object 6 is disposedon the upper side of the expansible film 4. Edges of the pressuresensitive adhesive sheet 10 for producing chip are fixed by means of thering frame 5 on the pressure sensitive adhesive layer 1 for setting theobject 6 at its periphery. The object 6 is set on the pressure sensitiveadhesive layer 1 for setting the object 6 inside its periphery.

In the present invention, it is especially desirable to employ thepressure sensitive adhesive sheet 10 for producing chip with thestructure of FIG. 1 or FIG. 2.

The process for producing a chip according to the present invention willbe described below using the pressure sensitive adhesive sheet 10 forproducing chip shown in FIG. 1. The object 6 is set on the pressuresensitive adhesive layer 1 for setting the object 6 of the pressuresensitive adhesive sheet 10 for producing chip. The pressure sensitiveadhesive sheet 10 for producing chip is fixed by means of the ring frame5, and the object 6 is cut (diced) into chips 7.

The object 6 to be diced includes, for example, a semiconductor waferhaving a circuit formed thereon such as Si wafer, Ge wafer and GaAswafer;

a ceramic plate such as alumina, zirconia, silicon nitride and siliconcarbide, insulating substrate and electronic devices;

a glass plate, quartz and the like used as optical element;

a wiring board such as printed circuit board;

a lead frame made of iron or copper;

a tape for TAB (tape automated bonding);

resin molded articles; and

composite devices of the above, such as a semiconductor mounted on thelead frame, resin sealed thereof and resin sealed semiconductor mountedon the tape to TAB.

The cutting depth is preferably such that the shrinkable film 2 iscompletely cut while the cutting of the expansible film 4 is haltedbefore reaching the middle thereof (see FIG. 8). The shrinkagerestricting force is weakened by the complete cutting of the shrinkablefilm 2, so that the shrinking performance of the shrinkable film 2 canfully be exerted at zone designated “8” in FIG. 8 (namely, outside thezone for setting the object 6 and inside the zone where the pressuresensitive adhesive sheet 10 for producing chip is fixed).

Subsequently, the shrinkable film 2 is shrunk by appropriate meansrequired. When a thermally shrinkable film is employed, the shrinkage ofthe shrinkable film 2 is effected by heating the laminate of the chips 7and the pressure sensitive adhesive sheet 10 for producing chip at 60 to150° C.

The above shrinkage of the shrinkable film 2 causes the pressuresensitive adhesive layer 1 for setting the object 6 disposed thereon todeform in conformity with the shrinkage of the shrinkable film 2, sothat not only is the area in which the chips 7 are in contact with thepressure sensitive adhesive layer 1 for setting the object 6 reduced butalso the chip spacings are uniformly enlarged in both longitudinal andlateral directions (see FIG. 9). This is because, referring to FIG. 9, ashrinking stress (indicated by the arrow in FIG. 9) is generated in theshrinkable film 2 at noncut part 8 which is present between the zone forsetting the object and the ring frame 5 for fixing the pressuresensitive adhesive sheet 10 for producing chip, so that a tension isapplied into the expansible film 4 with the result that the expansiblefilm 4 is drawn toward the ring frame 5. Consequently, the same effectas that exerted by expanding the pressure sensitive adhesive sheet 10for producing chip is obtained. Therefore, the chip spacings areuniformly enlarged, so that desirable bonder recognition can be realizedwithout the need to carry out the expansion step.

When the pressure sensitive adhesive sheet 10 for producing chipaccording to the present invention is employed in the production of achip such as a slender line sensor, it is preferred that a uniaxiallyoriented film be used as the shrinkable film 2 with the direction oforientation thereof brought into agreement with the direction of shortside of the chip from the viewpoint that the chip spacing difference isdecreased between the longitudinal and lateral directions. The use of abiaxially oriented film is preferred for chips whose short and longsides are identical with each other or approximate to each other fromthe viewpoint that, also, the chip spacing difference is decreasedbetween the longitudinal and lateral directions.

Moreover, in the present invention, the ratio of shrinkage of theshrinkable film 2 can be controlled by appropriately setting shrinkageconditions (temperature, time, etc.) of the shrinkable film 2, so thatthe ratio of expansion of the chip spacing can easily be changed.

Composing the pressure sensitive adhesive layer 1 for setting the object6 of an ultraviolet curable pressure sensitive adhesive is especiallypreferred from the viewpoint that the adhesive strength thereof can bereduced by irradiating the pressure sensitive adhesive layer 1 forsetting the object 6 with ultraviolet rays prior to or after the aboveshrinkage to thereby cure the pressure sensitive adhesive layer 1 forsetting the object 6. The curing of the pressure sensitive adhesivelayer 1 for setting the object 6 enables further reducing the verticalpeeling strength with the result that the pickup of the chips 7 isfacilitated.

The pressure sensitive adhesive sheet for producing chip of the presentinvention is suitably used in the above process for producing a chip andcomprises a zone for setting an object to be diced including anexpansible film 4 and a pressure sensitive adhesive layer 1 for settingthe object 6 and a shrinkage zone including at least one layer ofshrinkable film 2, wherein the shrinkage zone is arranged at leastoutside the zone for setting the object.

Examples of the pressure sensitive adhesive layers 1 for setting theobject 6, shrinkable films 2 and expansible films 4 are the same asdescribed hereinbefore. The bonding of the shrinkable film 2 and theexpansible film 4 may be executed either with the use of theabove-mentioned adhesive 3 or by direct means such as heat sealing.

Exemplary structures of the pressure sensitive adhesive sheets forproducing the chips according to the present invention are as shown inFIGS. 1 to 7. Of these, it is especially preferred to employ thestructure of FIG. 1 or FIG. 2.

That is, especially preferred pressure sensitive adhesive sheet forproducing chip according to the present invention is, for example, onewherein the pressure sensitive adhesive layer 1 for setting the object6, the shrinkable film and the expansible film are laminated on entiresurfaces in this order as shown in FIG. 1 or one wherein the pressuresensitive adhesive layer 1 for setting the object 6, the expansible filmand the shrinkable film are laminated on entire surfaces in this orderas shown in FIG. 2.

Further, it is preferred that the expansible film have an elasticmodulus of less than 1×10⁹ N/m².

Still further, it is preferred that the pressure sensitive adhesivelayer 1 for setting the object 6 is composed of a radiation curablepressure sensitive adhesive. Still further, it is preferred that theshrinkable film and the expansible film are laminated via an adhesivelayer having an elastic modulus of at least 1.0×10⁵ N/m².

The pressure sensitive adhesive sheet for producing chip of the presentinvention can suitably be employed in uses other than for producing achip as described above, for example, for temporary fixing of electronicdevice products and surface protection.

EFFECT OF THE INVENTION

In the present invention, satisfactory uniform chip spacings can beobtained without the problems of tearing of a pressure sensitiveadhesive sheet for producing chip and unsatisfactory chip spacings. Thepressure sensitive adhesive sheet for producing chip of the presentinvention is free from deformation in the thickness direction, so thatit is most suitable for automization of a production line. Moreover, theratio of expansion of chip spacings can freely be controlled byappropriately setting shrinkage conditions such as temperature and timeot thereby enable attaining a productivity enhancement.

EXAMPLE

The present invention will be illustrated in detail below with referenceto the following Examples which in no way limit the scope of theinvention.

In the following Examples and Comparative Example, the chip spacing andthe chip alignment were evaluated in the following manner.

Chip Spacing

An 8 inch silicon wafer was set on the pressure sensitive adhesive layer1 for setting the object 6 of the pressure sensitive adhesive sheet forproducing chip produced in each of the following Examples andComparative Example, and the pressure sensitive adhesive sheet forproducing chip was fixed by means of a ring frame. The wafer was dicedby the customary procedure into 10 mm×10 mm IC chips.

Thereafter, the pressure sensitive adhesive sheet for producing chip washeat treated at 90° C. for 1 min. Further, chip spacings after the heattreatment (in lateral direction (=X) and longitudinal direction (=Y) onorientation flat of the wafer) were measured by the use of an opticalmicroscope.

Chip Alignment

The chip alignment was evaluated by the following formula using the dataobtained in the measurement of the chip spacing.${{Chip}\quad {alignment}} = \frac{{Standard}\quad {deviation}\quad {of}\quad {chip}\quad {spacings}}{{Average}\quad {value}\quad {of}\quad {chip}\quad {spacings}}$

(The smaller value indicates excellent chip alignment.)

Example 1

1(1) Production of Pressure Sensitive Adhesive 1 for Setting the Object:

100 parts by weight of an acrylic pressure sensitive adhesive (copolymerof n-butyl acrylate and acrylic acid), 200 parts by weight of a urethaneacrylate oligomer having a molecular weight of 7000, 10 parts by weightof a crosslinking agent (isocyanate type) and 10 parts by weight of anultraviolet curable reaction initiator (benzophenone type) were mixedtogether, thereby obtaining an ultraviolet curable pressure sensitiveadhesive composition for setting the object.

1(2) Adhesive 3 for Films Bonding:

A polyurethane type adhesive (elastic modulus of 3.0×10⁸ N/m²) was usedas the adhesive for films bonding.

1(3) Lamination of Shrinkable Film and Expansible Film:

An expansible ethylene/methacrylic acid copolymer film (having athickness of 100 μm and an elastic modulus of 2.15×10⁸ N/m²) was coatedwith the adhesive of step 1(2) above so that the thickness of thecoating was 5 μm and heated at 100° C. for 30 seconds. Thereafter, athermally shrinkable polyethylene terephthalate film (having a thicknessof 30 μm and a shrinkage ratio of 50% at 120° C.) was laminated to theadhesive side of the above coated ethylene/methacrylic acid copolymerfilm, thereby obtaining a laminate of shrinkable film and expansiblefilm.

1(4) Production of Pressure Sensitive Adhesive Sheet for Producing Chip:

A 25 μm thick polyethylene terephthalate film having undergone releasetreatment was coated with the pressure sensitive adhesive compositionobtained in step 1(1) above so that the thickness of the coating was 10μm and heated at 100° C. for 1 min, and was bonded to the side ofshrinkable film of the laminate obtained in step 1(3) above. A circle of270 mm in diameter was cut therefrom, thereby obtaining an ultravioletcurable pressure sensitive adhesive sheet for producing chip 10 havingthe structure of FIG. 1.

The results are given in Table 1.

Example 2

2(1) Production of Pressure Sensitive Adhesive 1 for Setting the Object:

An ultraviolet curable pressure sensitive adhesive composition wasproduced in the same manner as in step 1(1) of Example 1.

2(2) Lamination of Shrinkable Film to Pressure Sensitive Adhesive Layer:

A 25 μm thick polyethylene terephthalate film having undergone releasetreatment was coated with the pressure sensitive adhesive compositionobtained in step 2(1) above so that the thickness of the coating was 10μm and heated at 100° C. for 1 min. Thereafter, a thermally shrinkablepolyethylene terephthalate film (having a thickness of 30 μm and ashrinkage ratio of 50% at 120° C.) was bonded to the pressure sensitiveadhesive side of the coated polyethylene terephthalate film, therebyobtaining a shrinkable film having a pressure sensitive adhesive layer.

2(3) Production of Adhesive for Films Bonding:

100 parts by weight of an acrylic pressure sensitive adhesive (copolymerof n-butyl acrylate and acrylic acid) and 2 parts by weight of acrosslinking agent (isocyanate type) were mixed together, therebyobtaining an adhesive composition for films bonding. The resultingadhesive had an elastic modulus of 1.0×10⁵ N/m².

2(4) Lamination of Adhesive for Films Bonding to Expansible Film:

A 25 μm thick polyethylene terephthalate film having undergone releasetreatment was coated with the adhesive composition produced in step 2(3)above so that the thickness of the coating was 25 μm and heated at 100°C. for 1 min. Thereafter, an expansible ethylene/methacrylic acidcopolymer film (having a thickness of 100 μm and an elastic modulus of2.15×10⁸ N/m²) was laminated to the adhesive side of the above coatedpolyethylene terephthalate film.

2(5) Production of Pressure Sensitive Adhesive Sheet for Producing Chip:

While peeling the release treated polyethylene terephthalate film fromthe adhesive layer of expansible film produced in step 2(4) above, theadhesive layer side of the expansible film was bonded to the side havingno pressure sensitive adhesive layer of shrinkable film having pressuresensitive adhesive layer produced in step 2(2) above. A circle of 270 mmin diameter was cut therefrom, thereby obtaining an ultraviolet curablepressure sensitive adhesive sheet for producing chip 10 having thestructure of FIG. 1.

The results are given in Table 1.

Example 3

A peelable type pressure sensitive adhesive sheet for producing chip wasproduced in the same manner as in Example 2, except that a peelable typepressure sensitive adhesive composition comprising 100 parts by weightof an acrylic pressure sensitive adhesive (copolymer of n-butyl acrylateand 2-hydroxyethyl acrylate) and 10 parts by weight of a crosslinkingagent (isocyanate type) was used as the pressure sensitive adhesivecomposition for setting the object.

The results are given in Table 1.

Example 4

4(1) Production of Pressure Sensitive Adhesive 1 for Setting the Object:

An ultraviolet curable pressure sensitive adhesive composition wasproduced in the same manner as in step 1(1) of Example 1.

4(2) Lamination of Expansible Film to Pressure Sensitive Adhesive Layer1:

A 25 μm thick polyethylene terephthalate film having undergone releasetreatment was coated with the pressure sensitive adhesive compositionobtained in step 4(1) above so that the thickness of the coating was 10μm and heated at 100° C. for 1 min. Thereafter, an expansiblepolyethylene/methacrylic acid copolymer film (having a thickness of 100μm and an elastic modulus of 2.15×10⁸ N/m²) was laminated to thepressure sensitive adhesive side of the coated polyethyleneterephthalate film.

4(3) Production of Adhesive for Films Bonding:

An adhesive composition for films bonding was produced in the samemanner as in step 2(3) of Example 2. 4(4) Lamination of adhesive forfilms bonding to shrinkable film:

A 25 μm thick polyethylene terephthalate film having undergone releasetreatment was coated with the adhesive composition produced in step 4(3)above so that the thickness of the coating was 25 μm and heated at 100°C. for 1 min. Thereafter, a shrinkable polyethylene terephthalate film(having a thickness of 30 μm and a shrinkage ratio of 50% at 120° C.)was bonded to the pressure sensitive adhesive layer side of the coatedpolyethylene terephthalate film, thereby obtaining a shrinkable filmhaving an adhesive layer.

4(5) Production of Pressure Sensitive Adhesive Sheet for Producing Chip:

While peeling the release treated polyethylene terephthalate film fromthe adhesive layer of shrinkable film produced in step 4(4) above, theadhesive side of the shrinkable film was bonded to the side having nopressure sensitive adhesive layer of the expansible film having thepressure sensitive adhesive layer produced in step 4(2) above. A circleof 270 mm in diameter was blanked therefrom, thereby obtaining anultraviolet curable pressure sensitive adhesive sheet 10 for producingchip having the structure of FIG. 2.

The results are given in Table 1.

Example 5

A peelable type pressure sensitive adhesive sheet for producing chip wasproduced in the same manner as in Example 4, except that a peelable typepressure sensitive adhesive composition as same as Example 3 was used asthe pressure sensitive adhesive composition for setting the object.

The results are given in Table 1.

Example 6

6(1) Production of Pressure Sensitive Adhesive 1 for Setting the Object:

An ultraviolet curable pressure sensitive adhesive composition wasproduced in the same manner as in step 1(1) of Example 1.

6(2) Lamination of Expansible Film to Pressure Sensitive Adhesive Layer:

An expansible film having a pressure sensitive adhesive layer composedof the pressure sensitive adhesive composition prepared in step 6(1) wasproduced in the same manner as in step 4(2) of Example 4.

6(3) Production of Adhesive for Films Bonding:

An adhesive composition was produced in the same manner as in step 2(3)of Example 2.

6(4) Lamination of Adhesive for Films Bonding to Shrinkable Film:

The shrinkable film was laminated to the films bonding adhesive layer ofstep 6(3) in the same manner as in step 4(4) of Example 4. A circle wascut therefrom, thereby obtaining a shrinkable film having adhesive layerwith a hole of 210 mm in inside diameter.

6(5) Production of Pressure Sensitive Adhesive Sheet for Producing Chip:

While peeling the release treated polyethylene terephthalate film fromthe shrinkable film having adhesive layer produced in step 6(4) above,the adhesive side of the shrinkable film was bonded to the side havingno pressure sensitive adhesive layer of the expansible film havingpressure sensitive adhesive layer produced in step 6(2) above. A circleof 270 mm in diameter being concentric with the above hole was blankedtherefrom, thereby obtaining an ultraviolet curable pressure sensitiveadhesive sheet for producing chip having the structure of FIG. 6.

The results are given in Table 1.

Example 7

7(1) Production of Pressure Sensitive Adhesive 1 for Setting the Object:

A peelable pressure sensitive adhesive composition was produced in thesame manner as in step 3(1) of Example 3.

7(2) Lamination of Expansible Film to Pressure Sensitive Adhesive Layer:

An expansible film having a pressure sensitive adhesive layer composedof the pressure sensitive adhesive composition prepared in step 7(1) wasproduced in the same manner as in step 4(2) of Example 4.

7(3) Production of Pressure Sensitive Adhesive for Immobilizing RingFrame:

A pressure sensitive adhesive composition having the same composition asin step 2(3) of Example 2 was produced.

7(4) Lamination of Pressure Sensitive Adhesive for Immobilizing RingFrame to Shrinkable Film:

The same procedure as in step 6(4) of Example 6 was repeated except thatthe pressure sensitive adhesive composition obtained in step 7(3) abovewas applied in a thickness of 10 μm, thereby obtaining a shrinkable filmhaving a pressure sensitive adhesive layer of step 7(3) with a hole of210 mm in inside diameter.

7(5) Production of Pressure Sensitive Adhesive Sheet for Producing Chip:

While peeling the release treated polyethylene terephthalate film fromthe peelable pressure sensitive adhesive layer of expansible filmproduced in step 7(2) above, the pressure sensitive adhesive side of theexpansible film was bonded to the side having no pressure sensitiveadhesive layer of the shrinkable film having pressure sensitive adhesivelayer produced in step 7(4) above. A circle of 270 mm in diameter beingconcentric with the above hole was blanked therefrom, thereby obtaininga peelable type pressure sensitive adhesive sheet for producing chiphaving the structure of FIG. 3.

The results are given in Table 1.

Comparative Example 1

The same procedure as in Example 2 was repeated except that theexpansible substrate was replaced by a nonexpansible substrate(polyethylene terephthalate film of 100 μm in thickness having anelastic modulus of 4.53×10⁹ N/m²).

The results are given in Table 1.

TABLE 1 Chip spacing (μm) Chip alignment X-axis Y-axis X-axis Y-axisExample 1 850 850 0.06 0.07 Example 2 750 750 0.13 0.17 Example 3 750750 0.20 0.21 Example 4 400 400 0.20 0.23 Example 5 400 400 0.25 0.30Example 6 250 250 0.28 0.30 Example 7 250 250 0.36 0.38 Comparative  35 35 0.41 0.42 Example

What is claimed is:
 1. A process for producing a chip, comprising the steps of: setting an object to be diced on a pressure sensitive adhesive sheet comprising at least one layer of shrinkable film, an expansible film and a pressure sensitive adhesive layer for setting the object; fixing edges of the pressure sensitive adhesive sheet; dicing the object into chips, completely cutting the shrinkable film located at a zone for setting the object and leaving said shrinkable film located between the zone for setting the object and the fixed edges uncut; and shrinking the shrinkable film located between the zone for setting the object and the fixed edges to thereby expand chip spacings.
 2. The process as claimed in claim 1, wherein, during the dicing step, the expansible film is partially cut.
 3. A process for producing a chip comprising the steps of: setting an object to be diced on a pressure sensitive adhesive sheet comprising an expansible film, a pressure sensitive adhesive layer including a zone for setting an object to be diced, and at least one layer of a shrinkable film, wherein a shrinkage area formed by the shrinkable film is at least partially located outside of said zone for setting the object to be diced; fixing edges of the pressure sensitive adhesive sheet; dicing the object into chips; and shrinking the shrinkable film located between the zone for setting the object and the fixed edges to thereby expand chip spacings. 